Condensers filled with R-22 refrigerant can no longer be legally sold. There are some companies which sell dry units. The unit is then filled with R-22 when it is installed. The price of R-22 has been increasing each year. It may be more expensive in your situation to buy an R-22.

How do you currently heat your house? Why do you need a back up unit?

Mike,
I have two Nat Gas Furnaces. One is a backup. Why? When I bought the house 8 years ago, the 5-ton Carrier had a compressor failure the second week after I moved in. It was 1 month from warranty expiration, but my dealer found a replacement compressor for free, that would take 2 weeks to get in and get installed. This was during Texas 100F summer time. I had a new 5-ton Coleman scroll put in that very day, split the ducts with electronic air dampers, and then had a new main HVAC, with a spare HVAC 1 month later when the compressor for the Carrier arrived and could get scheduled to be installed. I prefer the situation as-is, as a week or two of no A/C will either make you move North, or send you to a hotel. Probably why I have a whole-house generator that gets more use, especially during hurricanes, than any of my neighbors would have believed, at least until I had A/C and lights when they did not for two and 1/2 weeks during IKE. I like to be comfortable, and be able to keep my Dobermans inside and comfortable:-)

Now is the time to make the jump to R-410 Puron refrigerant. Go 13 SEER with matching coil. Since this will be backup, just stick to a builders grade model.

IMO